This invention relates to pressure limiting valves in general and more particularly to an improved pressure limiting valve.
Pressure limiting valves having a valve disk which is connected to a rod-like guide member and which is pressed against a passage opening by the force of a coil spring resting against an abutment are known. In a particular valve of this nature shown in the French Pat. No. 1596,326, the valve abutment is supported by a setting screw which applies a force eccentrically to the abutment. The guide member passes through the coil spring as well as the opening in the abutment, the guide member being movably guided in the hole of a holding means fixed to the housing.
It has been discovered that, in such pressure limiting valves, the valve disk tends to oscillate when the flow volume of the medium flowing through the valve changes suddenly. Such oscillations must be damped in a suitable manner in order to avoid damage to the valve. U.S. Pat. No. 2,564,815 teaches a ball valve in which a guide rod is pressed against the sphere closing the valve opening by means of a coil spring. The guide rod itself is guided in two holes which are axially offset with respect to each other. By means of an additional screw, which pushes laterally against the coil spring and thus exerts a transversal force on the it, the guide rod is pushed against the one side wall of the two holes and thereby exerts friction at the hole. This friction damps oscillations which occur.
A design of this nature has various disadvantages. Since the pressure force of the additional screw is transmitted to the guide rod through the coil spring, the guide rod can execute transversal vibrations if the valve is shocked; the guide rod then no longer rests against the side wall of the hole temporarily and the desired friction is no longer produced. In addition, the transversal force exerted on the coil spring by the additional screw must always be separately adjusted in accordance with the response pressure of the valve. This means that the transversal force exerted by the additional screw also must be changed accordingly when the response pressure of the valve is changed by an adjustment of the abutment of the spring. Such special adjustments are very difficult for the valve user and as a result full damping effect is not always achieved.